1. Field of the Invention
The field of this invention is within the art of breathing gas regulators. It pertains to those breathing gas regulators that are often referred to as demand or second stage regulators that regulate an intermediate pressure that can be used by a party breathing from a self contained breathing apparatus. More particularly, the invention incorporates a second stage regulator having a diaphragm which can be made in part of an elastomeric material which flexes inwardly and outwardly upon a user's breathing.
2. Description of the Prior Art
The prior art of self contained breathing apparatus (SCBA's) relies upon a source of breathing gas such as a pressurized tank of air. The pressurized tank is connected to a first stage or high pressure regulator to regulate the high pressure. From the first stage regulator, a connection is made to a second stage or demand regulator.
The second stage regulator is such wherein a user can breath the breathing gas from the second stage or demand regulator upon inhalation. Such second stage regulators are often used in conjunction with masks for purposes of providing breathing gas under pressure free from contaminants.
As can be appreciated, self contained breathing apparatus is often used in fire and rescue work as well as in industrial environments where certain atmospheres would be deleterious to a user.
The use of such fire, rescue and industrial self contained breathing apparatus is such where it is often exposed to contaminated gases that can attack certain portions of a regulator over an extended period of time. Such contaminated gases and contaminants can be in the form of those gases that are currently known with regard to chemical warfare. Also, certain deleterious gases and contaminants can be generated from industrial fires, explosions, and other conditions. Such chemical contaminants can affect a user of self contained breathing apparatus such as a fireman or an industrial clean-up worker.
Another problem with regard to self contained breathing apparatus in severe environments where contaminants are being used pertains to those gases in chemical warfare. One of these gases is known as Sarin gas. Also, chemical, biological, radiological and nuclear contaminants can affect a mask adversely. This is particularly true when the mask and the breathing apparatus relies upon an elastomeric diaphragm in order to effect the demand regulator functions as is known in the prior art.
Contaminants such as Sarin gas and other deleterious substances can affect such elastomeric diaphragms adversely. The diaphragms are often times made of an elastomeric material, whether it be silicone rubber or other types of elastomerics which are subject to deterioration when exposed to such gases and contaminants.
Elastomers generally have a matrix which can create interstices in adverse environments when contaminants are exposed to the surface of such elastomers. In effect, the contaminants disperse into the rubber and are then eventually transmitted to the other side to one degree or the other.
It has been found that such contaminants can permeate the diaphragm of a demand regulator over a given period of time. However, with the use of this invention, it has substantially extended that period of time.
Self contained breathing apparatus is usually under positive pressure within the mask and in the regulator area in order to exclude any contaminants from seeping into the mask. By maintaining a positive pressure within the mask above ambient or atmospheric pressure, the seal around a user's face and the other areas can exclude contaminants and other deleterious gases. As can be understood, a simple contaminant such as smoke, if leaked into the mask, could cause a severe problem for a fireman or industrial worker.
It has been found that when the air within the portion overlying the regulator diaphragm is protected from ambient conditions it will protect the diaphragm. By substantially excluding contaminants from coming into the regulator over the diaphragm, it will increase longevity of the diaphragm.
An SCBA regulator normally has a diaphragm which is exposed to ambient and flexes upon inhalation. Exposure to the ambient conditions is such where deleterious gases and contaminants can reach the surface of the elastomeric diaphragm. When these gases and contaminants are substantially eliminated by a bellows or expansion and contraction member, it has been found that a greater degree of longevity can be encountered with the diaphragm lasting longer.
This invention is directed toward increasing the longevity of a regulator diaphragm by a sealing bellows or expansion and contraction member. Breathing gas or a compressible fluid is retained above the diaphragm and substantially displaces deleterious gases and contaminants from over the diaphragm of the SCBA demand regulator. The bellows or expansion and contraction member provides a protective cover, while at the same time allowing differential pressure movements of the diaphragm. This allows operation of the regulator diaphragm while at the same time protecting it.